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Mathematics
From DEPSSA WiKi

USE OF GEOMETRICAL INSTRUMENTS
Introduction
Every object in this universe has definite shape and has definite Geometrical figure. These geometrical figures can be easily understand by the best use of Geometrical Instruments. First of all you should be familiar with each instrument contained in Geometry Box. After that you must know which instrument is used for drawing, measuring different Geometrical Shaped figures and objects.
Friends! What is the shape of this room?
Can we measure its dimensions?
Which Geometrical instruments can help us in this work?
Objectives
After going through this module you will be able to:
 Encourage students to increase Geometrical knowledge through Geometrical Instruments.
 Improve the knowledge of Geometry for teachers through demonstration.
 Explain the best use of Geometrical Instruments while teaching to students.
Geometrical Instruments
Aware the students about importance of having Geometrical Instruments with each and use frequently.
Types of Geometrical Instruments at Elementary Level
There are five basic Geometrical Instruments.
 Scale
 Compass
 Protractor
 Divider
 Set Squares
Let us watch a video film based on the above discussion
Self Check Exercise
Each student should be familiar with above Instruments.
a) What is Geometry Box?
b) How many Instruments it has?
c) Name these Instruments.
d) What are their uses at Primary stage?
e) Do you know about their uses in detail?
Uses of Geometrical Instruments
Explanation of Use of Geometrical Instruments through Video
So many uses of mathematical Instruments are.we explain here in brief.
Scale
Scale can be used to draw Ray, Line, Line Segments and measure length, breadth, height etc in various units of length e.g. Inch, Centimeter, Millimeter etc.
Compass
Compass can make some angles 0  360 degree. It can also make other Geometrical parameters like Line Segment, Arc, Circle, Perpendicular, Parallel Lines and many more Geometrical diagrams.
Protractor
To measure and draw angles 0  360 degree particularly which can not be drawn with compass.
There are many uses of Protractor like so.To draw Perpendicular, Line Segments, Semi Circle, Dividing Line Segments, Angles etc Protractor can be used.
Two shapes (Semi Circular & Circular shape)of Protractors are in use. Semi Circular shaped Protractor looks like D.So it is also called D.
Divider
To Measure Line Segment, Comparison of Line Segments, Angles and their Division etc use of divider can save time .
Set Squares
Triangular shaped two types of Set Squares are there.one has angles 90 degree, 45 degree, 45 degree other has angles 90 degree, 60 degree, 30 degree called 45 degree and (60 degree/ 30 degree) Set Squares respectively.These can be used to draw perpendicular, Parallel Lines some angles without use of Protractor and Compass, Scale etc.Using 1,2 or more Set Squares at a time many geometrical figures like Right, Equilateral, Isosceles Triangles, Rectangle, Square, Parallelogram, Rhombus, Trapezium etc can be draw quickly and can easily by students.
Any Geometrical construction is not possible without use of Geometrical instruments.
For more information of Geometrical Instruments. You can refer the web site in the given below
Self Check Exercise
You are requested to answer the following question:
a) Draw line Segments 6.7 cm, 3 inches in length.
b) Draw angle of 75 degree with help of Compass. and 55 degree with help of Protractor.
c) Divide with divider 6cm line Segment into 3 equal parts.
d) Draw a line AB now through a given point P outside AB draw a line II(Parallel)to given line with Set Squares.
e) From a given line segment 8.4cm a point P is given. At a distance 40 mm through P draw lines parallel to given line segment with Compass and Set Squares both.
Unit Summary
To get recapitulation of above text ask for their uses. If some students don't succeed try again some improved procedure with Instrumental demonstration briefly.
References
SCERT Gurgaon Haryana(2000), Use of Geometry Box why & how?
DEP SSA IGNOU New Delhi (Dec. 2009) Teaching of Mathematics at Upper Primary Level Volume II
Contributors
MR. Mukesh Kumar Mrs. Darshna Duhan
Lecturer Work Experience Lecturer Mathematics DIET Moti Bagh, DIET Gurgoan New Delhi Hayana